<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        // 形式为 ...变量名
        function add(...arg){
            console.log(arg);
            let sum = 0;
            arg.forEach(function(item){
                sum += item;
            })
            return sum;
        }
        add(1,2,3,4,5)

        function ass(a,b,...arg){
            console.log(a);
            console.log(b);
            console.log(arg);
        }
        ass(1,2,3,4,5,6,7,8,9)
    </script>
</body>
</html>